(a) Technical Field
The present invention relates to an apparatus for warning a pedestrian of a vehicle using directionality of a dipole sound source of acoustics.
(b) Background Art
Recently, due to the development of the electric vehicle, many other various technologies have begun to be developed to work along side or with the electric vehicle to make the electric vehicle a safer vehicle for both pedestrians and drivers. Accordingly, since electric vehicle are effectively soundless in comparison to an internal combustion engine, thus it is difficult for pedestrians outside the vehicle to hear an electric vehicle approaching. Therefore, electric vehicles have an increasing likelihood of pedestrian collision.
Therefore, notification systems for pedestrians have begun to be developed. For example, an access warning apparatus that generates an appropriate access sound based on the speed of the vehicle, a distance from the pedestrian, and surrounding light intensity has been developed to improve pedestrian safety.
In these devices, components of some technologies introduced to generate appropriate access sound are connected to a speaker through 1) a vehicle speed and distance detecting unit, 2) a pronunciation unit, 3) an optical detector, a light intensity calculating unit, and a driving circuit unit.
Another, exemplary technology utilizes an apparatus that prevents accidents by outputting an engine sound through the speaker depending on the revolutions per minute (RPM) of a driving motor by storing various acoustic data related an engine in a database and providing playback of those sounds based upon the motors current RPMs. This system warns a pedestrian that an electric vehicle is approaching the pedestrian. This system includes a vehicle speed sensor, a human response sensor, an operating switch and a display device. An RPM of the electric vehicle, voltage, current, variable resistance are detected by the system and a driving motor RPM detecting unit is connected to the speaker via an acoustic generator and an amplifier through a control unit.
However, in the above solutions, a general speaker is used and thus the sound cannot be effectively transferred to the pedestrian. The reason is that directionality of sound generated from the speaker cannot be set because refraction and interference occur within a monopole type sound source. Further, since the sound has no directionality, when a speaker volume is increased to transfer the sound to the pedestrians effectively, the driver's indoor noise deteriorates, thus having a reverse effect.
Matters described as the background art are just to improve the background of the present invention, but it should not be understood that the matters correspond to the related art which has been already known to those skilled in the art.